Insulation gas filled encapsulated high voltage electrical conductor

ABSTRACT

A high-voltage electrical conductor is encapsulated within an insulation gas filled rectilinear tubular casing and supported centrally within the casing by longitudinally spaced supportinsulators each of which is provided with three radially directed legs spaced 120* apart about the conductor. Two of the legs have fixed positions on the insulator structure but the third leg is spring-loaded for movement in the radial direction from a retracted, latched position to a radially outward unlatched position. A carriage running on wheels or rolls is used to transport the insulator-conductor structure into the casing with the third leg in its retracted, latched position and with the outer ends of all three legs spaced from the casing wall so that no undesirable contact therebetween takes place during the transporting operation. When the insulator has reached the desired position of installation, the latch for the third leg is released causing this leg to move outward and press firmly against the casing wall accompanied by a like movement of the other two fixed legs into pressure contact with the casing wall.

Floessel [54] INSULATION GAS FILLED ENCAPSULATED HIGH VOLTAGE ELECTRICAL CONDUCTOR [75] Inventor: Dieter Floessel, Fislisbach,

Switzerland [73] Assignee: Brown Boveri & Company Limited,

Baden, Switzerland Notice: The portion of the term of this patent subsequent to June 12, 1990,

has been disclaimed.

[22] Filed: July 18, 1972 [21] Appl. No.: 272,875

[30] Foreign Application Priority Data Sept. 13, 1971 Switzerland 13295/71 [52] U.S. Cl... 174/28, 174/13, 174/16 B,

[51] Int. Cl. H0lh 9/04 [58] Field of Search 174/13, 15 C, 16 B,

174/27, 28, 29, 25, 88 B, 99 B, 111; 13,8/l13,114,121,122

[56] References Cited UNITED STATES PATENTS 3,688,015 8/1972 Graybill 174/16 B 3,221,097 1l/l965 Cognet et a1... 174/99 B 2,355,111 8/1944 Rouault. 174/28 2,191,071 2/1940 Duttera 174/28 1,978,649 10/1934 Roberts 174/27 UX 3/1943 France 174/28 Primary Examiner-Bernard A. Gilheany Assistant Examiner-A. T. Grimley Attorney-Ralph B. Parker et a1.

[57] ABSTRACT A high-voltage electrical conductor is encapsulated within an insulation gas filled rectilinear tubular casing and supported centrally within the casing by longitudinally spaced support-insulators each of which is provided with three radially directed legs spaced 120 apart about the conductor. Two of the legs have fixed positions on the insulatorstructure but the third leg is spring-loaded for movement in the radial direction from a retracted, latched position to a radially outward unlatched position; A carriage running on wheels or rolls is used to transport the insulator-conductor structure into the casing with the third leg in its retracted, latched position and with the outer ends of all three legs spaced from the casing wall so that no undesirable contact therebetween takes place during the transporting operation. When the insulator has reached the desired position of installation, the latch for the third leg is released causing this leg to move outward and press firmly against the casing wall accompanied by a like movement of the other two fixed legs into pressure contact with the casing wall.

4 Claims, 4 Drawing Figures l1lXIIIf"/17I l/lIlI/Il/l/I/[I/l/II INSULATION GAS FILLED ENCAPSULATED HIGH VOLTAGE ELECTRICAL CONDUCTOR The present invention relates to an improvement in the construction of insulation gas-filled tubular encased i.e. encapsulated high-voltage electrical conductor. More particularly, the invention concerns an enclosed high-voltage conductor of the general type wherein the conductor is held in place centrally within a rectilinear, grounded metallic casing by means of support insulators which are spaced longitudinally along the conductor.

Enclosed high-voltage conductor structures of this type are known to the industry, reference being made, for example, to the diclosure in'U.S. Pat. No. 2,428,051 wherein the conductor is supported by three legs uniformly spaced about the conductor, i.e. 120 apart in the same plane, and which extend radially into engagement with the inner wall surfaceof the cylindrical enclosing casing structure. The inner-ends of the legs are fastened to the conductor and the outer ends are provided with spring means which enable the legs to be maintained in place by spring-loaded frictional contact with the inner wall surface of the casing. This construction, however, suffers from the disadvantage that when the insulator-conductor structure is inserted within the casing, a certain amount of abrading unavoidably takes place as the spring components slide under radial pressure along the inner wall surface of the casing with the result that small bits and chips of metal collect within the casing. However, without anexceedingly high cost, it is impossible to remove all of such impurities from the interior of the casing, with the result that the electrical stability of the high-voltage line is adversely affected.

The principal objective of the present invention is to provide an improved multi-leg support insulator construction for encased high-voltage conductors which avoids the disadvantages of the prior known constructions and which enables the multi-leg support to be inserted into the enclosing casing without any abrading effect; The objective is attained in that an initial clearance is provided between all of the legs of the multi-leg support and the inner wall of the casing to permit abrasion-free insertion of the support to its appointed location within the casing, following which at least one leg of the multi-leg' support is shifted radially to engage the inner wall of the casing and develop a pressurized, holding contact between all of the legs of the support and casing.

More particularly, the insulator support consists of a central tubular body portion which surrounds and is supported by the conductor structure and three legs which extend radially outward and are adapted to engage the inner wall of the casing but only after the insulator and conductor structure has been inserted into its proper position within the casing. In the illustrated embodiment of the invention, two of the three legs have fixed positions relative to the central body portion of the insulator and the thirdleg is movable in the radially outward direction under springpressure when released. A wheeled carriage is utilized to transport the insulator-conductor assembly into the casing with all three legs out of contactwith the casing wall and the crriage is provided with means by which the spring-loaded leg is automatically released from its radially inward position when the carriage is withdrawn so that all three legs then take positions in pressure contact with the casing wall.

It is known from the disclosure in US. Pat. No. 3,361,870 which relates to a three-phase power transmission line to suspend and transport the conductors individually, or jointly with a tubular casing with the assistance of rails and trolleys. However, this suspension and moving system remains permanently within the casing during operation of the line, an arrangement which is therefore quite expensive. However, in accordance with the present invention, the carriage by which the insulater-conductor structure is transported into place within the casing is removed after installation and hence does not become a permanent fixture of the high-voltage line within the casing. The foregoing as well as other objects and advantages inherent in the invention will become more apparent from the following detailed description of one suitable embodiment and the accompanying drawings wherein:

FIG. la is a longitudinal central section through a portion of the encased high-voltage conductor taken on line a a of FIG. lb showing the tri-leg insulator in the installed position, v

FIG. lb is a transverse section taken on line b b of FIG. 1a,

FIG. 2a is a longitudinal control section of the same portion of the encased conductor structure taken on line a a of FIG. 2b with the tri-leg insulator still supported on the carriage and with the spring loaded third leg of the insulator still held in its radially retracted position, and y FIG. 2b is a transverse section taken on line b b of FIG. 2a

With reference now to the drawings in which like components in the several views are designated by like reference numerals, the earthed tubular casing which surrounds the high-voltage conductor is indicated at 1 and is metallic, preferably aluminum. The conductor structure is tubular and is constituted by conductor section 2 and 3 joined in essentially end tO-end relation by means of a coupling sleeve 4 which encloses the end portions of the conductor sections and establishes an expansion joint to accommodate temperature-induced expansion and contraction of the conductor sections. An angle piece 5 secured to the end of conductor section 2 and a similar angle piece 6 secured to the end of conductor sections 3 function in conjunction with flexible conductor strap 7 secured at its opposite ends to the angle pieces to provide the necessary current conductive path between the adjacent conductor sections.

Surrounding and supported by the coupling sleeve 4 is the hub portion of the tri-leg insulator. Integral with this hub portion are two legs 8 which extend radially and are spaced l20apart. The third leg 9 of the in sulator suppor is, however, arranged for movement in a radial direction with respect to the hub portion 8c and the other two legs 8 and is seen to pass completely through the coupling sleeve 4 and the angle piece 5. The end of the upperportion 9b of leg 9 as viewed in the drawings is engageable with the inner wall of easing l and the lower portion is reduced in cross-section to form a stem which is surrounded by a compression spring 10, one end of which bears against a shoulder formed by the junction between the upper and lower portions 9b, 9c, the other end of this apring bearing against the end of strap 7 which rests upon the ,face of the angle piece 5. The lower end of leg 9 terminates in a head 11 which, as shown in FIGS. 2a, 2b is adapted to be engaged by an open-ended slot 12a provided in the chassis of a wheeled carriage 12 by which the insulator-conductor structure is installed within the casing.

In the transport position depicted in FIGS. 20, 2b and detail A" it will be seen that the head 11 of insulator leg 9 is held in a retracted, latched position by engagement with the slot 12a and with the spring 10 compressed. In this position of transport, the outer ends of all three legs 8, 8, 9 of the insulator do not touch the wall of casing l but rather gaps 8a, 9a are established therebetween so that the insulator-conductor structure can be freely transported on carriage 12 within the casing without danger of contact with the wall. When the insulator reaches the location desired for it, carriage 12 is withdrawn to the left, as viewed in FIG. 2a by any suitable means such as the rope 13 secured thereto with the result that the head 11 of insulator leg 9 is unlatched from the open end of slot 12a thus permitting the counter force stored within the compressed spring 10 to move insulator leg 9 from its retracted position to the radially outer position depicted in FIG. 1a so as to force itself against the wall of the casing and also cause the other two fixed legs 8, 8 to be forced against the casing wall with the result that the entire insulator structure is firmly held in place against the casing wall.

After installation of the insulator-conductor structure within casing l, the latter is then filled with the pressurized insulating gas, such as SE, at a pressure of four atmospheres.

l claim:

1. An encapsulated gas-filled high-voltage electrical conductor structure comprising a'rectilinear tubular metallic gas-filled casing, a rectilinear electrical conductor extending longitudinally within said casing, and at least one support insulator structure for centering said conductor within said casing and securing it against longitudinal displacement therein, said support insulator structure comprising at least three legs mounted on said conductor and extending radially in different directions therefrom in a common plane, the outer ends of a plurality of said legs secured to said conductor in fixed position and atleast another one of said legs being movable in a radical direction from a spring-loaded retracted and latched position wherein clearance is established between the outer ends of all of said legs and the inner surface of said casing to a radially outward unlatched position effective to cause all of said legs to engage and bear against the inner surface of said casing under the spring loading of said radially movable leg.

2. An encapsulated gas-filled high-voltage electrical conductor structure as defined in claim 1 wherein said support insulator structure is constituted by three radially extending legs spaced apart about the axis of said conductor.

3. An encapsulated gas-filled high-voltage electrical conductor structure as defined in claim 1 wherein said support insulator structure includes a hub portion mounted in place on said conductor and three radially extending legs spaced 120 apart about the axis of said conductor, two of said legs being secured in fixed position on said hub portion and the third leg including a loading spring thereon and which extends completely through said hub portion, one end of said third leg being engageable with the inner surface of said casing and the other end thereof including a head portion engageable in an open-ended latching slot provided on a carriage to maintain said third leg in its spring-loaded retracted and latched position until said carriage is withdrawn.

4. An encapsulated gas-filled high-voltage electrical conductor structure as defined in claim 3 wherein said conductor is constituted by adjacent sections connected together by means of a coupling sleeve providing an expansion joint therebetween, the end of each conductor section being provided with an angle piece providing anchors respectively for the opposite ends of a flexible conductor strap extending therebetween, and wherein the hub portion of said support insulator is secured in fixed position on said coupling sleeve, said loading spring surrounding a reduced portion of said third leg and having one end thereof bearing against a shoulder formed at the end of said reduced portion, the opposite end of said loading spring bearing against a fixed abutment formed by the combined engaged surfaces ofthe corresponding end of said flexible conductor strap and the angle piece. 

1. An encapsulated gas-filled high-voltage electrical conductor structure comprising a rectilinear tubular metallic gas-filled casing, a rectilinear electrical conductor extending longitudinally within said casing, and at least one support insulator structure for centering said conductor within said casing and securing it against longitudinal displacement therein, said support insulator structure comprising at least three legs mounted on said conductor and extending radially in different directions therefrom in a common plane, the outer ends of a plurality of said legs secured to said conductor in fixed position and at least another one of said legs being movable in a radial direction from a spring-loaded retracted and latched position wherein clearance is established between the outer ends of all of said legs and the inner surface of said casing to a radially outward unlatched position effective to cause all of said legs to engage and bear against the inner surface of said casing under the spring loading of said radially movable leg.
 2. An encapsulated gas-filled high-voltage electrical conductor structure as defined in claim 1 wherein said support insulator structure is constituted by three radially extending legs spaced 120* apart about the axis of said conductor.
 3. An encapsulated gas-filled high-voltage electrical conductor structure as defined in claim 1 wherein said support insulator structure includes a hub portion mounTed in place on said conductor and three radially extending legs spaced 120* apart about the axis of said conductor, two of said legs being secured in fixed position on said hub portion and the third leg including a loading spring thereon and which extends completely through said hub portion, one end of said third leg being engageable with the inner surface of said casing and the other end thereof including a head portion engageable in an open-ended latching slot provided on a carriage to maintain said third leg in its spring-loaded retracted and latched position until said carriage is withdrawn.
 4. An encapsulated gas-filled high-voltage electrical conductor structure as defined in claim 3 wherein said conductor is constituted by adjacent sections connected together by means of a coupling sleeve providing an expansion joint therebetween, the end of each conductor section being provided with an angle piece providing anchors respectively for the opposite ends of a flexible conductor strap extending therebetween, and wherein the hub portion of said support insulator is secured in fixed position on said coupling sleeve, said loading spring surrounding a reduced portion of said third leg and having one end thereof bearing against a shoulder formed at the end of said reduced portion, the opposite end of said loading spring bearing against a fixed abutment formed by the combined engaged surfaces of the corresponding end of said flexible conductor strap and the angle piece. 